2018-01-12

#hackAAS number 6

Today was the 6th annual AAS Hack Day, at #AAS231 in Washington DC. (I know it was 6th because of this post.) It was an absolutely great day, organized by Kelle Cruz (CUNY), Meg Schwamb (Gemini), and Jim Davenport (UW & WWU), and sponsored by Northrup Grumman and LSST. The Hack Day has become an integral part of the AAS winter meetings, and it is now a sustainable activity that is easy to organize and sponsor.

My hack for the day was to work on dimensionality and structure in the element-abundance data for Solar Twins (we need a name for this data set) created by Megan Bedell (Flatiron). I was reminded how good it is to bring data sets to the Hack Day! Several others took the data to play with, and Martin Henze (SDSU) went to town, visualizing (in R) the covariances (empirical correlations) among the elements. Some of these correlations are positive, some are negative, and some are tiny. Indeed, his analysis sort-of chunks the elements up into blocks that are related in their formation! This is very promising for my long-term goals of obtaining empirical nucleosynthetic yields.

What I did for Hack Day was to visualize the data in the natural (element-abundance) coordinates, and then again in PCA coordinates, where many of the variances really vanish, so the data really are low dimensional (dammit; my loyal reader knows that I don't want this to be true). And then I also visualized in random orthonormal coordinates (which was fun); this shows that the low-variance PCA space is indeed a very rare or hard-to-find subspace in the full 33-dimensional element space. I also visualized some rotations in the space, which forced me to do some 33-dimensional geometry, which is a bit challenging in a room of enthusiastic hackers!

But so much happened at the hack day. There was a project (led by aforementioned Bedell) to make interactive web-based plots of the exoplanet systems, to visualize multiplicity, insolation, and stellar properties. There was a project to find the “Kevin Bacon of astronomy” which was obviously flawed, since it didn't identify yours truly. But it did make a huge network graph of astronomers who use ORCID. Get using that, people! Erik Tollerud did more work on his hack-of-hacks to build great tools for collecting and recording hacks, but he also was working on a white paper for NASA about software licensing. I gave him some content and co-signed it. MIT for the win. Foreman-Mackey led a set of hacks in which astronomers learned how to use TensorFlow, which uses NVIDIA GPUs for insane speed-up in linear-algebra operations. Usually people use TensorFlow for machine learning, but it is a full linear-algebra library, with auto-differentiation baked in.

The AAS-WWT people were in the house, and Jonathan Fay, as per usual at Hack Days (what a hacker!), pushed a substantial change to the software, to make it understand and visualize velocity maps. Another group (including Schwamb, mentioned above) visualized sky polygons in WWT, and used a citizen-science K2 discovery as its test case for visualizing a telescope focal-plane footprint. There were nice hacks with APIs, with people learning to use the NASA Astrophysics Data System API and Virtual Observatory APIs, and getting different APIs to talk together. One hack was to visualize Julia Sets using Julia! It took the room a few minutes to get the joke, but the visualization was great, and very few lines of code in the end. And there were at least two sewing hacks.

None of this does justice: It was a packed room, about 1/3 of the participants completely new to Hack Days, and great atmosphere and energy. I love my job!